1. Field of the Invention
The present invention relates generally to pipes and more specifically to a method of internally restoring a pipe, which provides a cost effective alternative to replacing or making exterior repairs to the pipe.
2. Discussion of the Prior Art
A method of restoring small diameter pipe systems (the Process), utilizing compressed air for cleaning and internal coating pipes, has been well known worldwide since at least the late 1970′s. The Toyo Lining Company received an approval from the Japanese government to restore water pipe systems in 1981. Since 1987, the Naval Research Laboratory has been involved in the development and testing of coatings for the in-place lining of piping systems. The process is commonly known as the “Air-Sand” lining process and has been utilized by the Navy to restore and protect the piping in its ships and land-based facilities, both commercial and residential.
The real life application of the process to restore aging building water systems has had many challenges. These challenges are well documented within the US Navy report titled ‘Control of Lead in Drinking Water’ from 1997 among others. The difficulty of insuring that the dry sandblasting material is cleared from the pipe system after the cleaning operation; restriction and plugging of pipe tee's and pipe intersections with excess coating material; and the inability of the process to seal leaks is well known to those in the art.
To seal other than the smallest of leaks in systems of pipes with the Process has not been possible. Compressed air application of an internal liquid epoxy coating results in the coating being forced out the leak opening without sealing the leak. U.S. Pat. No. 6,739,950 to Kruse states in col. 6, lns. 51-52 that ‘If major leaks are discovered, a repair is performed prior to starting the pipe coating procedure.’ The Navy literature also teaches the repair of leaks before application of internal coatings.
More recently alternate methods for sealing leaks in systems of pipes installed within buildings have been taught. U.S. Pat. No. 5,622,209 to Naf discloses a process for sealing and internal repair of systems of laid conduits. The Naf process is implemented by flooding the piping system with water and a mixture of fillers including water swellable bentonite. If the known problem of clearing the dry cleaning media proved problematic in the prior art, the removal of the bentonite and filler loaded solution suggested by Naf would be at least equally a challenge if not impossible. It will not be practical to clear a pipe system once this material is introduced and allowed to set to the point of sealing the leaks. The uncleared sealing media taught by Naf will necessarily result in restricted and plugged pipe sections.
U.S. Pat. Nos. 7,858,149 and 8,033,242 to Gillanders et al. both disclose methods and systems for coating and sealing inside piping systems in one step. Claims are made that the addition of fiber and other fillers to the liquid coating material in ratios up to 50% by volume will seal holes up to 0.125″ (⅛″) during the process of internal coating of the pipe system. One skilled in the art understands that during the compressed air application of liquid epoxy to the inside of a small diameter pipe any filler included in the liquid epoxy will be separated by the action of the airflow and moved to the front of the lining stream. In the process of coating the inside of small diameter water pipe systems in houses and commercial buildings, liquid coating is injected with compressed air from multiple inlet points progressing toward a single outlet. The individual ‘shots’ of coating material introduced into each successive outlet are not measured to clear the system of pipes, just to coat an individual portion of the system, thus the filler load of each ‘shot’ of coating will remain within the system causing a significant reduction in internal pipe diameter, compromise the intended lining thickness, and result in an inferior finished product.
Accordingly, there is a clearly felt need in the art for a method of internally restoring a leaking pipe, which provides a cost effective alternative to replacing or making exterior repairs to a pipe, and which utilizes airflow measurements and airflow control inside a pipe to optimize the repair of a leak with the application of an internal restoration coating.